<!DOCTYPE html>
<html class="reftest-wait">
  <head>
    <title>displaystyle</title>
    <meta charset="utf-8">
    <link rel="help" href="https://mathml-refresh.github.io/mathml-core/#the-displaystyle-and-scriptlevel-attributes">
    <link rel="help" href="https://mathml-refresh.github.io/mathml-core/#style-change-mstyle">
    <link rel="help" href="https://mathml-refresh.github.io/mathml-core/#underscripts-and-overscripts-munder-mover-munderover">
    <link rel="help" href="https://mathml-refresh.github.io/mathml-core/#operator-fence-separator-or-accent-mo">
    <link rel="help" href="https://mathml-refresh.github.io/mathml-core/#legacy-mathml-style-attributes">
    <link rel="help" href="https://mathml-refresh.github.io/mathml-core/#fractions-mfrac">
    <link rel="match" href="displaystyle-014-ref.html"/>
    <meta name="assert" content="Test dynamic change of mathbackground on an operator does not interfer with its displaystyle">
    <script type="text/javascript">
      function doTest() {
        document.body.offsetTop; // Update layout
        document.getElementById('mathOperator').
                 setAttribute('mathbackground', 'red');
        document.documentElement.removeAttribute("class");
      }
      window.addEventListener("load", () => { document.fonts.ready.then(doTest); });
    </script>
    <link rel="stylesheet" href="/fonts/ahem.css">
    <style>
      math {
          font: 25px Ahem;
      }
    </style>
  </head>
  <body>

    <!-- See https://bugzilla.mozilla.org/show_bug.cgi?id=832800 -->
    <math>
      <mstyle displaystyle="true">
        <mfrac>
          <mrow>
            <mn>X</mn>
            <mo id="mathOperator">+</mo>
            <mfrac>
              <mrow><mn>X</mn></mrow>
              <mrow><mn>X</mn></mrow>
            </mfrac>
          </mrow>
          <mrow>
            <mn>X</mn>
          </mrow>
        </mfrac>
      </mstyle>
    </math>

    <script src="/mathml/support/feature-detection.js"></script>
    <script>MathMLFeatureDetection.ensure_for_match_reftest("has_mfrac");</script>
  </body>
</html>
